OzVMX Forum
Marque Remarks => CZ => Topic started by: tony27 on September 17, 2014, 01:35:14 pm
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Are wiseco pistons any good in CZs, I have a reed ported cylinder coming which has a brand new wiseco piston with holes cut in the skirt to match the needs of the reed valve. I plan on trying it at some stage using the GEM reed block
From photos it appears that they only run a single ring unlike the genuine which is easily gotten for about $120us
(http://i788.photobucket.com/albums/yy166/tony27_photo/CZ%20981%20random%20stuff/GEM%20reed/Wisecopistonwithreedcutouts_zpsf2bbe32a.jpg) (http://s788.photobucket.com/user/tony27_photo/media/CZ%20981%20random%20stuff/GEM%20reed/Wisecopistonwithreedcutouts_zpsf2bbe32a.jpg.html)
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I would think those tiny holes would do jack, I'd be making larger round holes (round holes not having any corners for cracks to start from), finished a little nicer. I'd also grind an arc on the bottom of the skirt, although you can't go far because the holes are so low.
I'd also be looking down the intake port to see how wide the piston holes can be before going past the edge of the port.
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What were the holes cut with a tommahawk? The holes just allow a path into the crankcase, but the holes need to be exposed to the reed around TDC
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Not so sure about the holes either, the 1 drawing I have seen regarding holes in the piston for reed valves on CZs had from memory 13mm drilled holes.
Being a piston port motor standard the skirt is above the ports towards tdc Lozza, I guess these would be at close to bdc. From the photos of cylinder it appears that there are 2 extra boost ports machined to feed from the intake ports, would the holes be to allow some mixture in between when the intakes close & the transfers open?
I'm thinking a new genuine piston kit may be the best way to go, that way I can drill & radius to match the drawing
I had the reed block out of my yz465 today & was surprised to see the intake port closed off by the piston at btc, was expecting to see it open
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To me Wisecos are pistons of last resort,
Those windows certainly need some help
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Not so sure about the holes either, the 1 drawing I have seen regarding holes in the piston for reed valves on CZs had from memory 13mm drilled holes.
Being a piston port motor standard the skirt is above the ports towards tdc Lozza, I guess these would be at close to bdc. From the photos of cylinder it appears that there are 2 extra boost ports machined to feed from the intake ports, would the holes be to allow some mixture in between when the intakes close & the transfers open?
I'm thinking a new genuine piston kit may be the best way to go, that way I can drill & radius to match the drawing
I had the reed block out of my yz465 today & was surprised to see the intake port closed off by the piston at btc, was expecting to see it open
errm intake flow only happens from 90 deg btdc to tdc when the piston is rising no intake flow at bdc.
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So you're saying just get a new genuine piston & not bother with the holes?
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If you are going to run the reed .. you should have the holes... otherwise there is little or no benefit from the reed ..
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if you are going to run Seizeco do not use their piston to bore clearance (go wider) like as in you think your putting in a worn out piston :o run it in I mean as in really run it in, and use lots of oil, and rich on the carb ::) then seize it up, cost me an Aussie title,
probobably best to get it ceramic coated ;) better still get a few thou of ceramic put on you old piston as long as its in ok nick ie piston ring groove tolerances are in the servicable range
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If you are going to run the reed .. you should have the holes... otherwise there is little or no benefit from the reed ..
Actually a hinderance
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if you are going to run Seizeco do not use their piston to bore clearance (go wider) like as in you think your putting in a worn out piston :o run it in I mean as in really run it in, and use lots of oil, and rich on the carb ::) then seize it up, cost me an Aussie title,
probobably best to get it ceramic coated ;) better still get a few thou of ceramic put on you old piston as long as its in ok nick ie piston ring groove tolerances are in the servicable range
Bore it to Wiseco tolerances as per their instructions,
Run the piston as per their instructions,
Then pull it down again, wet rubbing any wear marking / high spots on the piston,
ALWAYS without exception warm up the engine before engaging the power band !!!
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So you're saying just get a new genuine piston & not bother with the holes?
With a reed it controls intake timing not the ports in the piston that helps fill the crank case. Run the piston just radius the ports in the piston.
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if you are going to run Seizeco do not use their piston to bore clearance (go wider) like as in you think your putting in a worn out piston :o run it in I mean as in really run it in, and use lots of oil, and rich on the carb ::) then seize it up, cost me an Aussie title,
probobably best to get it ceramic coated ;) better still get a few thou of ceramic put on you old piston as long as its in ok nick ie piston ring groove tolerances are in the servicable range
Bore it to Wiseco tolerances as per their instructions,
Run the piston as per their instructions,
Then pull it down again, wet rubbing any wear marking / high spots on the piston,
ALWAYS without exception warm up the engine before engaging the power band !!!
yep did that twice 1st time it tried to seize was on 1st start up it started squeeking after shut down when ya kicked it over, any who after 2 rub downs, was not happy with the marks appearing, so then took it out (honed) another thou or two, was assembled everytime with lots of oil, then run in alot, best part it didn't seize at the first race meeting it seized at the 2nd race meet ;)
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I know guys that have had the same issue, would run it in, re check everything and after a couple of meetings would seize.
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I know guys that have had the same issue, would run it in, re check everything and after a couple of meetings would seize.
;) gone back to original kit, hard to find so just shop for bits all the time now have some spares, but ya gotta admitt seizco are the piston that keep on giving or is that takeing :-[
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Like I said Piston of Last Resort
Use anything else First,
If nothing else available then use a Wiseco,
Warmed Run In and Clearance Checked.
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if you are going to run Seizeco do not use their piston to bore clearance (go wider) like as in you think your putting in a worn out piston :o run it in I mean as in really run it in, and use lots of oil, and rich on the carb ::) then seize it up, cost me an Aussie title,
probobably best to get it ceramic coated ;) better still get a few thou of ceramic put on you old piston as long as its in ok nick ie piston ring groove tolerances are in the servicable range
Bore it to Wiseco tolerances as per their instructions,
Run the piston as per their instructions,
Then pull it down again, wet rubbing any wear marking / high spots on the piston,
ALWAYS without exception warm up the engine before engaging the power band !!!
yep did that twice 1st time it tried to seize was on 1st start up it started squeeking after shut down when ya kicked it over, any who after 2 rub downs, was not happy with the marks appearing, so then took it out (honed) another thou or two, was assembled everytime with lots of oil, then run in alot, best part it didn't seize at the first race meeting it seized at the 2nd race meet ;)
None of the above you bake the piston at 200deg C for an 1.5 hours BEFORE the cylinder is bored. Have used many old cast Wiseco's in the blue boxes after doing, never seized, even running at the edge of detonation. Worst piston increased diameter by 3 thou
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I wonder how may of you guys are absoluteley certain about air leaks..??!!I have run many "old" Wiseco without any troubles..and really..running more oil??....only makes the mixture more lean..remember... it is the fuel the cools..the more oil..the less fuel.. so LEAN.. no wonder it seizes...
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Massively altering the oil from 50:1(2%) to 20:1(5%) is only using 3% more oil, 1 jet is typicaly 3% change in fuel flow.
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I've used plenty of wiesco pistons in both road bike drag bike and MX and never had an issue....
Yet I do no other people who have used them and had no luck at all...
I've also used JE pistons, Ross pistons, and Wossner as well all with good results...
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if you are going to run Seizeco do not use their piston to bore clearance (go wider) like as in you think your putting in a worn out piston :o run it in I mean as in really run it in, and use lots of oil, and rich on the carb ::) then seize it up, cost me an Aussie title,
probobably best to get it ceramic coated ;) better still get a few thou of ceramic put on you old piston as long as its in ok nick ie piston ring groove tolerances are in the servicable range
Bore it to Wiseco tolerances as per their instructions,
Run the piston as per their instructions,
Then pull it down again, wet rubbing any wear marking / high spots on the piston,
ALWAYS without exception warm up the engine before engaging the power band !!!
yep did that twice 1st time it tried to seize was on 1st start up it started squeeking after shut down when ya kicked it over, any who after 2 rub downs, was not happy with the marks appearing, so then took it out (honed) another thou or two, was assembled everytime with lots of oil, then run in alot, best part it didn't seize at the first race meeting it seized at the 2nd race meet ;)
None of the above you bake the piston at 200deg C for an 1.5 hours BEFORE the cylinder is bored. Have used many old cast Wiseco's in the blue boxes after doing, never seized, even running at the edge of detonation. Worst piston increased diameter by 3 thou
nope wasnt any old blue box, what we used was new , and no have not heard of bakeing the piston and no, no air leaks, will not use Seizco ever again, no doubt there has been some success from wiseco or the company would not be in business, just funny how I had my 1st seizure after 40 years and that was after being well informed with the for mentioned info and by the way it was from older and more experienced motorcycle specialist raceing machine shops, so Ill just go back to the manufacturers item and if Im going to dabble it will be with ceramics.
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Wisecos 4 stroke pistons are OK,
It's the old air cooled 2 smokes that have been the problems
Especially the Dykes ring models,
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Wisecos 4 stroke pistons are OK,
It's the old air cooled 2 smokes that have been the problems
Especially the Dykes ring models,
agreed ;)
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haven't had any problems with Wiseco for years.
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Got to love the way all the Experts agree on this forum.
I've seen lots of siezed pistons and barrells of all makes. Ninty nine time out of one hundred the people that bored them either thought they knew more about what clearance to give a piston than the piston manufacturer did or they simple do not know how to measure a piston to get the correct fit.
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The cylinder & piston arrived today, the 2 extra ports feed from the intakes & are nicely done. They look to be taller & steeper than the standard rear transfer.
The problem I need to sort is that the ends of the ring is midway across 1 of the new ports, a standard piston ends up with both end gaps over the new ports but there seems to be more meat available in the standard CZ piston for moving the pins. Is there a limit to how far apart the pins can be placed safely?
(http://i788.photobucket.com/albums/yy166/tony27_photo/CZ%20981%20random%20stuff/GEM%20reed/temporary_zpsefccfb7b.jpg) (http://s788.photobucket.com/user/tony27_photo/media/CZ%20981%20random%20stuff/GEM%20reed/temporary_zpsefccfb7b.jpg.html)
The new ports. Quite a bit of space between the main transfers & the boost ports to move the end of the rings to
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just funny how I had my 1st seizure after 40 years
Try harder ;)
The end gaps will run over those ports no problems if it runs through the middle of the port window. Don't move the pins it's a shite job and easy to go pear shaped.
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Like sleepy says I think it's more a problem with incorrect clearances, or not chamfering the ports, in correct ring gap, air or water cooled bikes never had a problem, I've got 3 bike that running wiseco pistons at the moment and all going well...
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I'd have to agree with Lozza on this one. I would make sure you have good chamfers on the ports in question and from the photo it looks like all the ports need a little more work on the chamfers. Some motors have the ring ends over small port from new, one that springs to mind are the bigger Maico's, 400 have the ring end in the middle of the rear transfer port and the 490's have it across the de-comp port.
Moving the pegs is only a last resort job, almost impossible to get out the old ones and the pins are hardened with some small grooves up the sides that let the air space behind the pins vent. I've seen a few pin moving jobs end in disaster when they came out. Some of the early Wiseco's with dykes rings would end up with loose pins after a long hard life.
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Got to love the way all the Experts agree on this forum.
I've seen lots of siezed pistons and barrells of all makes. Ninty nine time out of one hundred the people that bored them either thought they knew more about what clearance to give a piston than the piston manufacturer did or they simple do not know how to measure a piston to get the correct fit.
give Dave Dyson a ring and tell him that, do you know how long he has been in the raceing business?
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Over 40 years ago I spent many nights watching listening to Norm Fraser run 3 boring bars simultaneously many great stories and a boat load of fun.
Norm could bore anything including 750 Ducatis to 860cc long before the factory,
And a 700cc Pantah a year before the factory had the 600.
For Wisecos he had a very course cross hatch and run them in flat out after they were warm.
I sold both my boring bars 20 years ago, as a waste of space,
Lozza's idea of measuring a grown piston certainly is ideal but who would go to that trouble???